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/*
FreeRTOS.org V4.1.0 - Copyright (C) 2003-2006 Richard Barry.
This file is part of the FreeRTOS.org distribution.
FreeRTOS.org is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
FreeRTOS.org is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with FreeRTOS.org; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
A special exception to the GPL can be applied should you wish to distribute
a combined work that includes FreeRTOS.org, without being obliged to provide
the source code for any proprietary components. See the licensing section
of http://www.FreeRTOS.org for full details of how and when the exception
can be applied.
***************************************************************************
See http://www.FreeRTOS.org for documentation, latest information, license
and contact details. Please ensure to read the configuration and relevant
port sections of the online documentation.
***************************************************************************
*/
/*-----------------------------------------------------------
* Implementation of functions defined in portable.h for the Atmel ARM7 port.
*----------------------------------------------------------*/
/* Standard includes. */
#include <stdlib.h>
#include <intrinsic.h>
/* Scheduler includes. */
#include "FreeRTOS.h"
#include "task.h"
/* Constants required to setup the initial stack. */
#define portINITIAL_SPSR ( ( portSTACK_TYPE ) 0x3f ) /* System mode, THUMB mode, interrupts enabled. */
#define portINSTRUCTION_SIZE ( ( portSTACK_TYPE ) 4 )
/* Constants required to setup the PIT. */
#define portPIT_CLOCK_DIVISOR ( ( unsigned portLONG ) 16 )
#define portPIT_COUNTER_VALUE ( ( ( configCPU_CLOCK_HZ / portPIT_CLOCK_DIVISOR ) / 1000UL ) * portTICK_RATE_MS )
/* Constants required to handle critical sections. */
#define portNO_CRITICAL_NESTING ( ( unsigned portLONG ) 0 )
#define portINT_LEVEL_SENSITIVE 0
#define portPIT_ENABLE ( ( unsigned portSHORT ) 0x1 << 24 )
#define portPIT_INT_ENABLE ( ( unsigned portSHORT ) 0x1 << 25 )
/*-----------------------------------------------------------*/
/* Setup the PIT to generate the tick interrupts. */
static void prvSetupTimerInterrupt( void );
/* ulCriticalNesting will get set to zero when the first task starts. It
cannot be initialised to 0 as this will cause interrupts to be enabled
during the kernel initialisation process. */
unsigned portLONG ulCriticalNesting = ( unsigned portLONG ) 9999;
/*-----------------------------------------------------------*/
/*
* Initialise the stack of a task to look exactly as if a call to
* portSAVE_CONTEXT had been called.
*
* See header file for description.
*/
portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
{
portSTACK_TYPE *pxOriginalTOS;
pxOriginalTOS = pxTopOfStack;
/* Setup the initial stack of the task. The stack is set exactly as
expected by the portRESTORE_CONTEXT() macro. */
/* First on the stack is the return address - which in this case is the
start of the task. The offset is added to make the return address appear
as it would within an IRQ ISR. */
*pxTopOfStack = ( portSTACK_TYPE ) pxCode + portINSTRUCTION_SIZE;
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0xaaaaaaaa; /* R14 */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) pxOriginalTOS; /* Stack used when task starts goes in R13. */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x12121212; /* R12 */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x11111111; /* R11 */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x10101010; /* R10 */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x09090909; /* R9 */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x08080808; /* R8 */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x07070707; /* R7 */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x06060606; /* R6 */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x05050505; /* R5 */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x04040404; /* R4 */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x03030303; /* R3 */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x02020202; /* R2 */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x01010101; /* R1 */
pxTopOfStack--;
/* When the task starts is will expect to find the function parameter in
R0. */
*pxTopOfStack = ( portSTACK_TYPE ) pvParameters; /* R0 */
pxTopOfStack--;
/* The status register is set for system mode, with interrupts enabled. */
*pxTopOfStack = ( portSTACK_TYPE ) portINITIAL_SPSR;
pxTopOfStack--;
/* Interrupt flags cannot always be stored on the stack and will
instead be stored in a variable, which is then saved as part of the
tasks context. */
*pxTopOfStack = portNO_CRITICAL_NESTING;
return pxTopOfStack;
}
/*-----------------------------------------------------------*/
portBASE_TYPE xPortStartScheduler( void )
{
extern void vPortStartFirstTask( void );
/* Start the timer that generates the tick ISR. Interrupts are disabled
here already. */
prvSetupTimerInterrupt();
/* Start the first task. */
vPortStartFirstTask();
/* Should not get here! */
return 0;
}
/*-----------------------------------------------------------*/
void vPortEndScheduler( void )
{
/* It is unlikely that the ARM port will require this function as there
is nothing to return to. */
}
/*-----------------------------------------------------------*/
#if configUSE_PREEMPTION == 0
/* The cooperative scheduler requires a normal IRQ service routine to
simply increment the system tick. */
static __arm __irq void vPortNonPreemptiveTick( void );
static __arm __irq void vPortNonPreemptiveTick( void )
{
unsigned portLONG ulDummy;
/* Increment the tick count - which may wake some tasks but as the
preemptive scheduler is not being used any woken task is not given
processor time no matter what its priority. */
vTaskIncrementTick();
/* Clear the PIT interrupt. */
ulDummy = AT91C_BASE_PITC->PITC_PIVR;
/* End the interrupt in the AIC. */
AT91C_BASE_AIC->AIC_EOICR = ulDummy;
}
#else
/* Currently the IAR port requires the preemptive tick function to be
defined in an asm file. */
#endif
/*-----------------------------------------------------------*/
static void prvSetupTimerInterrupt( void )
{
AT91PS_PITC pxPIT = AT91C_BASE_PITC;
/* Setup the AIC for PIT interrupts. The interrupt routine chosen depends
on whether the preemptive or cooperative scheduler is being used. */
#if configUSE_PREEMPTION == 0
AT91F_AIC_ConfigureIt( AT91C_BASE_AIC, AT91C_ID_SYS, AT91C_AIC_PRIOR_HIGHEST, portINT_LEVEL_SENSITIVE, ( void (*)(void) ) vPortNonPreemptiveTick );
#else
extern void ( vPortPreemptiveTick )( void );
AT91F_AIC_ConfigureIt( AT91C_BASE_AIC, AT91C_ID_SYS, AT91C_AIC_PRIOR_HIGHEST, portINT_LEVEL_SENSITIVE, ( void (*)(void) ) vPortPreemptiveTick );
#endif
/* Configure the PIT period. */
pxPIT->PITC_PIMR = portPIT_ENABLE | portPIT_INT_ENABLE | portPIT_COUNTER_VALUE;
/* Enable the interrupt. Global interrupts are disables at this point so
this is safe. */
AT91F_AIC_EnableIt( AT91C_BASE_AIC, AT91C_ID_SYS );
}
/*-----------------------------------------------------------*/
void vPortEnterCritical( void )
{
/* Disable interrupts first! */
__disable_interrupt();
/* Now interrupts are disabled ulCriticalNesting can be accessed
directly. Increment ulCriticalNesting to keep a count of how many times
portENTER_CRITICAL() has been called. */
ulCriticalNesting++;
}
/*-----------------------------------------------------------*/
void vPortExitCritical( void )
{
if( ulCriticalNesting > portNO_CRITICAL_NESTING )
{
/* Decrement the nesting count as we are leaving a critical section. */
ulCriticalNesting--;
/* If the nesting level has reached zero then interrupts should be
re-enabled. */
if( ulCriticalNesting == portNO_CRITICAL_NESTING )
{
__enable_interrupt();
}
}
}
/*-----------------------------------------------------------*/
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